This is the time when we begin to find if the emotional power of the Newtown school shooting will translate into political change. People affected by mass shootings are now talking with state and federal lawmakers.

Susan Aaron's daughter escaped the shooting in Newtown after seeing her teacher and friends killed.

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SUSAN AARON: We stop being the world's greatest country when we allow our most vulnerable citizens to be slaughtered because we might offend people by taking away their guns.

INSKEEP: Aaron's told her story to Connecticut lawmakers, and so did Newtown resident Bill Stevens, who opposes tighter gun laws.

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BILL STEVENS: I'm very saddened at what happened in Sandy Hook as a dad, as I said. But I'm also saddened as a veteran to have to be here speaking on home soil in defense of our fundamental rights as Americans.

MONTAGNE: That was some of the testimony in Connecticut on the same day as a hearing in Washington, D.C. Lawmakers have spoken of changes, ranging from a ban on assault weapons, to better background checks.

CARRIE JOHNSON, BYLINE: For former Arizona Congresswoman Gabrielle Giffords, every step is a struggle. Giffords' right arm is paralyzed. She's also partially blind, the result of a point blank shooting two years ago at a Tucson shopping plaza where she met with constituents.

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GABRIELLE GIFFORDS: Violence is a big problem. Too many children are dying. Too many children. We must do something.

JOHNSON: Giffords read her statement from a piece of lined notebook paper, the kind that's so familiar in schools all over the country.

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GIFFORDS: It will be hard, but the time is now. You must act.

JOHNSON: The next four hours demonstrated exactly how hard it may be for the divided Senate to move ahead on new gun regulations.

Republicans raised doubts about a ban on assault weapons, an idea even many Democrats say won't fly in Congress. Several GOP senators also said they'd have a hard time supporting limits on high capacity magazines that carry dozens of rounds of ammunition.

Senator John Cornyn from Texas.

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SENATOR JOHN CORNYN: The federal government has a poor record of enforcing current laws, and I fail to see how passing additional laws that the Department of Justice will not enforce is going to make America any safer.

JOHNSON: Then there's the background check system. Under current law, only gun sales through federally licensed dealers get background checks, even though many sales now take place at gun shows, on the Internet, or through friends and family.

James Johnson - the police chief in Baltimore County, Maryland - told senators as many as four in 10 people never go through that system.

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CHIEF JAMES JOHNSON: Allowing 40 percent of those acquiring guns to bypass checks is like allowing 40 percent of passengers to board a plane without going through security. Would we do this?

JOHNSON: Speaking for a law enforcement coalition, Johnson asked senators to impose universal background checks that would cover private sales.

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JOHNSON: And if you think for a minute you could sell your gun to your neighbor that you've known for 10 years, you don't know your neighbor. You do not know your neighbor. And the only way to make sure that you're safe in what you're doing is a comprehensive background check.

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WAYNE LAPIERRE: You're creating an enormous federal bureaucracy.

JOHNSON: Wayne LaPierre is the chief executive of the National Rifle Association.

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LAPIERRE: It's only going to hit the law-abiding people, not criminals. Honest people are going to be entrapped into committing crimes they had no intention to commit, and it's going to - it's an unworkable universal federal nightmare bureaucracy.

JOHNSON: Days after the Newtown school shooting, LaPierre famously said the best way to stop a bad guy with a gun is a good guy with a gun. Before the Senate Judiciary Committee, he repeated his call for armed guards in schools.

Lindsey Graham's a Republican from South Carolina.

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SENATOR LINDSEY GRAHAM: We live in a world where there are four million high capacity magazines out there, or more. I think the best way to interrupt the shooter if they come to a school house is not to try to deny the woman in Atlanta the ability to have more than 10 rounds, but to have somebody like you, Chief Johnson, meet them when they come into the door.

JOHNSON: Mark Kelly, a retired astronaut who's married to Gabrielle Giffords, told lawmakers that could be dangerous. In Tucson two years ago, Kelly says, a Good Samaritan with a gun came within a split second of shooting someone other than the killer. Kelly says the issue's complex. But...

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MARK KELLY: One of our messages is simple: the breadth and complexity of gun violence is great, but it is not an excuse for inaction.

JOHNSON: Kelly shook hands with NRA executives as the hearing finally came to a close.

When it comes to action in the Senate, it's still not clear who has the upper hand.